Waves breaking on the shore.

Harnessing the motion of waves is one way to generate electricity from the ocean.

Image: CSIRO/Willem van Aken

It’s hard not to be impressed by the power of the ocean. The thunderous crash of waves during a storm and more gentle movements of the tides have captured many people’s imaginations. But the power of the ocean is not just poetic – it could literally be used to provide electricity.

Scientists around the world are researching new energy technologies that don’t rely on burning fossil fuels. This is because fossil fuel use releases carbon dioxide into the atmosphere, which can lead to climate change. Many alternatives being explored are renewable. One of these is ocean energy. As the name suggests, ocean energy uses the sea as its energy source.

In a fossil fuel power plant, substances such as coal or natural gas are burnt. The heat from this burning is used to boil water, which creates steam, which moves turbines. The turbines contain magnets, and their motion is what generates electricity.

Steam isn’t necessary to move a turbine. Theoretically any fluid can move a turbine, including seawater. The waters of the world’s oceans are constantly moving, and one way to get electricity from the ocean is to harness this constant motion.

Tides are the rise and fall of the sea level. They are caused by the gravitational influence of the Sun and Moon, as well as the Earth. The amount of water involved in tide changes can be huge. Tidal energy uses these water movements to drive turbines and generate electricity.

Waves are caused by wind transferring energy to the ocean’s surface. There are a number of different wave energy technologies being developed around the world that transfer the kinetic (moving) energy of waves to a turbine to create electricity.

Using the kinetic energy of the oceans is not the only way to obtain electricity from the ocean. Ocean thermal energy uses temperature differences between the surface and depths of the ocean. The warmer surface waters can be used to vaporise a liquid with a low boiling point, which in turn drives a turbine.

With the development of ocean energy technology, the sea could be a key source of our energy in the future.

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